This invention relates generally to the field of assays, and in particular to techniques to facilitate the performance of such assays in a high throughput manner. In one particular aspect, the invention relates to the organization of solid supports and/or organisms, such as cells, that are used in performing such assays.
The creation of large chemical libraries has led to the use of a wide variety of assays to evaluate such libraries. As is known in the art, such chemical libraries may be created using a variety of synthesizing techniques, such as those described in U.S. Pat. Nos. 5,503,805 and 5,708,153, the complete disclosures of which are herein incorporated by reference. Typically, such synthesizing processes utilize solid supports, such as small resin beads, onto which the chemicals are synthesized.
Because of the immense size of such libraries, it is desirable to find ways to evaluate the chemicals in a high throughput manner. However, this can be difficult due to the nature of many existing assay formats. For example, some assays involve the use of living mammalian cells or other organisms. This can be especially challenging because of the difficulty in handling and/or organizing the solid supports and the cells, as well as because of the need to provide nutrients to keep the cells viable.
Merely by way of example, one type of assay is a cell reporter assay utilizing cells that produce a signal upon activation of a receptor. Hence, if a chemical that is released from a solid support activates the receptor, a signal is produced. Standard detectors may then used to detect the signal. With such assays, the ability to screen large numbers of reactions while also maintaining cell viability can be especially challenging.
Another type of assay is a "bead marking" assay where libraries of compounds are released from beads and permitted to diffuse to inducible cells where they interact with target receptors and induce the cells to produce and secrete an enzyme. The enzyme diffuses back to the beads and "marks" them by metabolizing a substrate covalently attached to the beads. Such an assay is described generally in copending U.S. patent application Ser. No. 08/758,307, filed Mar. 12, 1996, now U.S. Pat. No. 5,958,703, the complete disclosure of which is herein incorporated by reference.
To enhance such an assay as a drug discovery tool, it would be desirable to minimize the number of falsely marked beads. For example, a bead can be falsely marked if it comes into physical contact with a cell. Another way is if a cell that was induced by a compound from a positive bead marks a bead with an inactive compound through excessive diffusion of a compound or enzyme.
Another group of assays that can pose challenges when utilized in a high throughput manner are competition assays that are based on the interference of the binding of two ligands. High throughput screening of such assays while maintaining cell viability can be difficult.
Hence, the invention is related to techniques to facilitate the performance of various assays that utilize solid supports and/or other organisms, such as cells, in an efficient manner. In this way, the invention provides for the screening of large chemical libraries in a high throughput manner using a wide assortment of assay formats.